Mode of preparing finely-divided or colloid indigo dyestuffs.



g1; ares @FFXCE ALBRECHT SCHMIDT AND ADOLF STEINDCRFF, OF H6CHST-0N-THE-MAIN, GERMANY,

ASSIGNORS TO FARBW'ERKE VORM. MEISTER LUCIUS 8: BRU'NING, OF H6CHST-ON- THE-MAIN, GERIVIANY, A CORPORATION OF GERMANY.

MODE O3? PREPARING FINELY-DIVIDED OR COLLOID INDIGO DYESTUFFS.

No Drawing. I

Specification of Letters Patent.

Application filed May 17, 1911.

Patented Apr. 28, 191 11. Serial No. 627,758.

To all iii/A0777, it may cone-cm:

Be it known that we, ALBRECHT SCHMIDT, Ph. D, chemist, and. Anon STEINDORFF, Ph, D., chemist, citizens of the Empire of Germany, residing at llt chst-o'n-the-lilain, Germany, have invented certain new and useful improvements in the Mode of Pro paring Finely-Divided or Colloid Indigo Dyestuffs, of which the following is a specification.

We have found that by producing indigo from indol derivatives which are closely related to indigo and capable of directly yielding indigo, in the presence of aromatic primary, secondary and tertiary bases and their derivatives, such as arylglycins or the like, and aromatic ammonium compounds, the indie-o precipitates in an extremely tincly-subdividcd colloid-like form. By the term indol derivatives which are closely related to indigo and capable of directly yielding indigo, we mean primarily indigo salts, comprising the salts of the dyestutl itself and those of its leuco compounds, that is to say, the leuco-indigo salts. Said aromatic bases act merely on the phys cal state of the indigo, like the aromatic sulfonic or carboxylic acids mentioned in United States Letters Patent 1,058,019 and 1,058,020, granted April 1, 1913, to Albrecht Schmidt, assignor.

Example: 100 parts by weight of anilinsulfate are dissolved in 3000 parts of sulfuric acid of 156., while stirring, and into this solution are strcwed at a tempera ture of 15 C. 262 parts of indigo, whereby indigo sulfate is innnediatelyformed. The indigo sulfate thus produced is then stirred for a short time (about one-half hour) with the excess of sulfuric acid and with the ani in sulfate, until a homogeneous mass is formed. The thick mixture of the reaction is poured into a large quantity of ice-water which may advantageously contain in solu tion slight quantities of carbohydrates or similar substances.

In the place of anilin there may be used corresponding quantities of, for instance, toluidins, dimethylanilin, benzylanilin, dibenzylauilin, phenylglycin, phenyldiglycin, plienylhydrazin, naphthylanin, czand l)- aminoanthraquinone or other primary, secondary or tertiary bases; also quaternary ammonium compounds, such as dimethylphenylbenzylannnoniuni-chlorid answer Very well.

laying now particularly described our invention what we claim is:

1. lihe process of preparing a new form of HyllthClJlC indi '0, which consists in subjecting derivatites of indol which are closely related to indigo and capable of directly yielding indigo, to indigoproducing conditions in the presence of aromatic bases.

2. The process of preparing a new form of synthetic indigo, which consists in pr0- ducing the indigo from indigo salts in the presence of aromatic bases.

3. The process of preparing a new form of synthetic indigo, which consists in producing the indigo from leuco-indigo salts in the presence of aromatic bases.

in testimony whereof, we aliix our signs tnres in presence of two witnesses.

ALBRECHT SCHMIDT. ADOLF STEINDORFF.

iv. tnesscs Juan GRUND 7 than GRUND.

I is hereby certified that in Letters Patent No. 1,09l,683, granted April 28, 191%, .N upon the application of Albrecht Schmidt and Adelf Steindorfi, o't' l'lijehston-lhe Main. tlernmny, to an hnprovelnent in lvlode ot' Preparing l inelwDn hled 0r Colloid indigo D \'e:-;tnii',s an" error appears in the printed specification requiring correction as follows: Line 51,101' the word naphthylanln read nap/1,t/tg/la m'in;

and. tlnrt t1e said Letters Patent should be read With this correction therein that the same may conform to the record of the ease in the Patent Oiliee.

Signed and sealed this 6th day of July, A. 1)., 191.5.

[Benn] R. F. WHITElt-XEAD,

Acting 00mm {Rs 07102 of 1' hunts. 

